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GENERAL INFORMATION AND CARE OF GENERATORS
1.
Use of Electric Motors
The
power
required
to
start
an
electr ic motor
is
considerably
more
than
is
required
for
keeping
it running after
it
1S
once
started.
Some motors require much more current to start them than
others.
Split phase
(A.C.) motors require more current to start
them,
under
similar
circumstances,
than other
types.
They are
commonly used on easy starting loads, such as washing machines or
where loads are applied after the motor is started such as small
power tools.
Since they require 5 to 7 times as much current to
start as to run, their use should be avoided whenever possible if
the
electric
motor
is
to
be
driven
by
a
small
generator.
Capacitor and repulsion-induction motors require from 2 to 4 times
as
much
current
to
start
them
as
to
run
them.
The
current
required to start any motor varies with the load connected to it.
An electr ic motor
connected
to an air
compressor,
for
example,
will require more than a motor to which no load is connected.
In general,
the current required
to start 115 volt motors con-
nected to medium starting loads will be approximately as follows:
MOTOR
AMPS FOR
AMPS FOR
SIZE
RUNNING
STARTING
1/6
3.2
6.4 to 22.4*
1/4
4.6
9.2 to 32.2*
1/3
5.2
10.4 to 72.8*
1/2
7.2
14.4 to 29.2
3/4
10.2
20.4 to 40.8
1
13
26
to 52
*Note that in the above table the maximum "amps for starting" is
more for some small motors than for larger ones.
This is because
the hardest starting types
(split-phase), are not made in larger
sizes.
Because the heavy surge of current required for starting motors is
required for only an instant, the generator will not be damaged if
it can bring the motor up to speed in a few seconds of time.
If
difficulty is experienced in starting motors,
turn off all other
electrical loads and, if possible, reduce the load on the electric
motor.
2.
Required Operating Speed
Although individual units and models may vary slightly, the normal
voltage and frequency of typical 60 cycle engine-driven generators
described in this book are approximately as follows when run first
vii th
no
load
applied,
then
at
half
the
generator
capaci
ty
and
finally
when
loaded
to
its
full
capacity
as
rated
on
the
nameplate.
31
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